Energy absorbers have often been customized or built in accordance with the requirements of the particular load conditions under which they were to perform. This is highly undesirable since building a shock absorber for each type of job is costly and time consuming. Further, customized shock absorbers are necessarily of many different sizes and there is generally no standardization among the individual components thereof, thereby making maintenance expensive and difficult.
To overcome the above disadvantage, several energy absorbers have been commercially manufactured which permit the energy absorbing capability thereof to be adjusted in accordance with the expected load conditions, thereby permitting the shock absorber to be utilized in many different loading and environmental conditions. While many of these adjustable energy absorbers have been adaptable to a wide range of load conditions, nevertheless these energy absorbers have not been as widely utilized as the area of need for same might indicate since they have been relatively costly. Specifically, most known adjustable energy absorbers have utilized a complex adjustment structure which is both expensive to manufacture and difficult to use. More specifically, these known shock absorbers have required an excessive amount of precise, and hence costly machining.
Also, many of the known adjustable shock absorbers use concentric, inner and outer control sleeves which are relatively movable for controlling flow between two chambers. However, these sleeves must be machined with extremely precise tolerances and/or machined as a matched pair in order to permit proper fit and opertion. This thus prevents random assembly of the parts, and hence substantially increases the cost of assembly.
Copending Application Ser. No. 608,885, filed Aug. 29, 1975, discloses therein an improved energy absorber, particularly a hydraulic shock absorber, which overcomes the abovementioned disadvantages. The shock absorber disclosed in this copending application, and particularly the embodiment illustrated in FIGS. 5-8, has proven to operate in a highly desirable and successful manner with respect to its energy absorbing capability and the adjustability thereof. However, in a continuing effort to improve upon this shock absorber, additional modifications have been made therein which are believed to improve the structural and operational characteristics thereof.
Thus, it is an object of this invention to provide an improved energy absorber which possesses the operational and structural characteristics of the energy absorber disclosed in the above-mentioned application, and which incorporates further improvements therein. For example, the energy absorber of this invention incorporates an improved adjustment structure to facilitate a simple yet precise adjustment between the control sleeves to vary the energy absorbing characteristic. Another improvement relates to the piston structure and particularly the manner in which pressure fluid is permitted to flow from behind the piston to permit a more rapid return thereof when the shock force is relieved. Still further improvements relate to the structure of the shock absorber so as to simplify the manufacture and assembly thereof, thereby minimizing the manufacturing cost, while at the same time maintaining the desirable operating characteristics.
Other objects and purposes of this invention will be apparent to persons familiar with structures of this type upon reading the following specification and inspecting the accompanying drawings.